One type of industrial control process is referred to as a batch process, which involves subjecting raw materials to processing steps using one or more pieces of equipment to produce a “batch” of product. Efforts to automate batch processing have led to the formation of standards committees by members of industries involved in batch processing and suppliers of batch processing equipment, among others. The general purpose of these standards committees has been to define uniform standards for automated batch processing. One such standard has been promulgated by the International Society for Measurement and Control, an international organization concerned with issues of process control. This standard is entitled Batch Control Part 1: Models and Terminology and is often referred to as the ISA S88.01-1995 standard (or “S88” for purposes of this application).
The S88.01 standard defines models of equipment and procedures for use in automated batch processes, as well as terminology for use in referring to those models and their elements. The S88.01 standard defines a “batch process” as a process that leads to the production of finite quantities of material by subjecting quantities of input materials to an ordered set of processing activities over a finite period of time using one or more pieces of equipment. A “batch” is defined as the material that is being produced or has been produced by a single execution of a batch process.
Batch-processing equipment (i.e., controllable elements such as valves, heaters, mixers, and so forth) is operated according to procedures to produce a batch. Generally, such equipment is referred to synonymously as equipment, equipment modules, processing equipment, or physical elements. The procedures to operate such physical elements are often referred to by the S88.01 standard as the “procedural model.” According to the S88.01 standard, the procedural model is structured as a hierarchical ranking of procedures, with the highest level encompassing each of the lower levels, the next highest level encompassing each of the levels below it, and so on. Typically, the levels of the S88.01 procedural model of a particular application are, in descending order: the “procedure;” the “unit procedure;” the “operation;” and the “phase.”
The term “procedural element” generally refers to components that employ any of the levels of the S88.01 procedural model, not just to those of the “procedure” level or any other single level of the procedural model. The highest-level procedural element of interest is referred to as a procedure, which is made up of one or more unit procedures. Each unit procedure is in turn made up of one or more operations, which are each in turn made up of one or more phases. The S88.01 procedural model does not preclude definition and use of other hierarchical levels, nor does it require that each level be present in particular applications. Rather, the standard is intended to provide a broad, standardized model for describing the procedures followed in automated batch-process control.
In a batch operation each device involved in production needs to be monitored, typically relying on timed events/operations since the state of a device is not always deterministic. Control systems adjust or tune timers that facilitate fault detection, the adjustment performed on a device by device basis for optimum operation performance. For example, a valve that is commanded to open/close as part of dispensing a fluid, such as milk, warm/cold water, or oil, in a recipe can have an associated timer adjusted (e.g., a time interval determined and associated with opening/closing the valve) to allow enough time for the commanded operation. Large batch processing operations can involve thousands of devices, thus adjusting and monitoring each of those devices can become an error-prone and costly operation, consuming significant personnel resources, time and funds.